A good technition has a scan tool to show what is exactly wrong with the srs sytem,find a techintion and dump the mechanic you have.
The brake pads squeel for the same reason ,the mechanic was supposed to add anti queel to the back of the pasd to keep them from dragging on the rotors and making noise, no blue/red anti squeel and you get noise.It is a 3 second .30 cent thing to do when changing brakes.
The smoke if it doens; smell is probably just vapour trapped in the vent system,nothign to worry about.
the leak needs to be found befroe it causes more problem. You would need to find what seal is gone and seal it again.